高纯纳米SiC粉体的糖碳转化绿色制造及其介电响应特性研究

As the direct raw material for high-performance SiC materials, the nanosized SiC powders with high purity have important scientific significance and engineering value for promoting the research, development and application of advanced SiC materials in many fields. The product grade upgrade and green low-cost manufacturing are the focus of research and development of this type of materials. This project will aim at these core problems and conduct the study on the optimization design and implementation method of preparation process for nanosized SiC powders with high purity. The novel method of carbohydrate-carbon conversion will be proposed to prepare carbohydrate-carbon shell on nanosized SiO2 surface in a green low-cost, quick and tunable way. The main controlling factors of nanosized SiO2 powders-carbohydrate solution with high solid content, low viscosity, great fluidity and stable dispersion will be revealed via the control on rheological properties of nanosized SiO2 powders-carbohydrate solution. The in-situ transformation mechanism of carbohydrate-carbon shell on nanosized SiO2 surface under hydrothermal condition will be elucidated, and the accurate control on composition and microstructure of SiO2- carbohydrate-carbon core-shell structure in a three-dimensional space could be achieved. The in-situ growth mechanism of nanosized SiC with high purity would be also uncovered during the pyrolysis process, and the optimization of preparation process for nanosized SiC powders with high purity would be obtained. The cooperation of quality improvement with green low-cost manufacturing of nanosized SiC powders with high purity could be realized.

高纯纳米SiC粉体作为高性能SiC材料的直接原材料，对于推动先进SiC材料在多个领域的研发和应用具有重要的科学意义和工程价值，品质提升和绿色低成本制备是该类材料研发的重点。本项目将针对这一核心问题，开展高纯纳米SiC粉体制备工艺的优化设计与实现方法研究，提出绿色低成本、快速可控的糖-碳转化新方法制备纳米SiO2表面糖碳壳层，通过调控纳米SiO2粉体-糖溶液流变特性，获得具有高固相含量、低粘度、良好流动性和稳定分散性的纳米SiO2粉体-糖溶液的主控因素；揭示水热条件下纳米SiO2表面糖碳壳层的原位转化机理，实现糖碳壳层包覆SiO2核壳结构在三维空间上组分与微结构的精细调控，阐明热解过程中高纯纳米SiC粉体原位生长机制，优化高纯纳米SiC粉体制备工艺，实现高纯纳米SiC粉体的品质提升与绿色低成本制造协同。

高纯纳米SiC粉体作为高性能SiC材料的直接原材料，对于推动先进SiC材料在多个领域的研发和应用具有重要的科学意义和工程价值，品质提升和绿色低成本制备是该类材料研发的重点。本项目针对这一核心问题，开展了高纯纳米SiC粉体制备工艺的优化设计与实现方法研究，首次提出了以碳包覆SiO2核壳结构为原料、碳热还原法制备纳米SiC粉体。主要研究结果如下：①揭示了具有高固相含量、良好流动性和稳定分散性的纳米SiO2粉体-糖溶液的主控因素，建立了纳米SiO2粉体-糖溶液流变特性调控方法，优选来源广泛、价格低廉葡萄糖作为原料，配置得到了糖液浓度为10wt.%，固相含量为5wt.%的高稳定纳米SiO2粉体-糖溶液，稳定时间超过48h；②阐明了水热条件下纳米SiO2表面糖碳壳层的原位转化机理，揭示了水热温度、pH值、糖液浓度、水热时间等反应参数对纳米SiO2粉体表面糖碳壳层形貌的影响规律，优选水热温度160℃、pH=7、糖液浓度10wt.%作为水热反应参数，通过对水热时间进行控制，实现了糖碳包覆SiO2核壳结构在三维空间上组分与微结构的精细调控；③阐明了碳热还原反应中从糖碳包覆SiO2核壳结构向纳米SiC粉体转变机制，揭示了碳热还原反应中反应温度和反应气氛对制备纳米SiC粉体的影响规律，优化了纳米SiC粉体制备工艺，在反应温度为1500℃、反应气氛为真空的条件下制备得到了纯度大于98%、粒径均匀、形貌近球形的高品质纳米SiC粉体，成本约5000元/kg，实现了纳米SiC粉体的品质提升与绿色低成本制造协同，通过调控原料纳米SiO2粉体的粒径，制备得到了粒径可控的纳米SiC粉体并揭示了粒径对其介电响应特性的影响规律，为纳米SiC粉体在高新技术领域的应用奠定了基础。本项目制备的高纯纳米SiC粉体已成功应用于团队研制的新型轻质防隔热复合材料，成功助力某型高速飞行器圆满完成首次飞行演示验证任务。

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